Kasey Kahne announced Tuesday that he has not been medically cleared to compete the rest of the NASCAR season, effectively ending his NASCAR career.

Kahne, 38, had previously announced this would be his last full-time NASCAR season.

Kahne has missed the last five races because of dehydration issues and had hoped to be cleared after a test last week at Charlotte Motor Speedway.

Instead, he was not.

“To say I’m disappointed after receiving the results that I was not medically cleared for the remainder of the season following a test session at Charlotte Motor Speedway last week is an understatement,” Kahne wrote in a tweet. “It was my hope that everything would go well and I would be able to finish out the season strong in the No. 95 for Leavine Family Racing. Unfortunately, that’s not the case.”

Kahne stated in his tweet that he is “perfectly healthy” out of the race car and that doctors have not determined any underlying health problems.

“My body just can’t handle extended periods of time in the race car and we weren’t able to control the sweat ratio to keep me hydrated enough to prevent any permanent damage to my body,” Kahne wrote.

Kahne said he would return to racing sprint cars, which compete in much shorter races. He ended a note to fans by saying:

“See you all soon at the dirt tracks, and thank you for sticking with me over the years.”

Kahne ends his NASCAR career with 18 Cup wins in 529 starts. He won the Coca-Cola 600 three times (2006, ’08 and ’12) and won the 2017 Brickyard 400 at Indianapolis Motor Speedway. He also was the 2004 Cup rookie of the year.

Kasey Kahne‘s NASCAR career is over after 15 year of Cup competition, but his racing career is far from over.

Kahne is scheduled to make more than 50 starts in sprint car races next year in the World of Outlaws and All-Star Circuit of Champions with his own sprint car team.

The news is part of a sponsor announcement that will have Kahne and Kasey Kahne Racing’s No. 9 car sponsored by Wicked Energy Gum/Wicked Energy in select races.

“This is the most excited I have been in a long time to get back to racing,” Kahne said in a press release. “I feel great and I’ve been working out a lot preparing for the upcoming season. Returning to sprint cars on a more regular basis is something that I have been looking forward to for years.”